Epibionts

Many pelagic organisms, including sea turtles, host unique communities of epibionts on the surfaces of their bodies. Although sea turtle epibiota have been studied in other areas of the world, very little research has been conducted on the epibionts found on sea turtles inhabiting the water around Bonaire, Netherland Antilles. In this study, epibiont samples were obtained from 33 sea turtles found in Bonaire. Epibionts included green and red algae, polychaete worms, skin barnacles, and turtle barnacles. Barnacle abundance and epibiont biodiversity was determined for each size class (Small, Medium, Large juveniles) of the two most common species of sea turtles found on Bonaire (Eretmochelys imbricata and Chelonia mydas). There was no significant difference in number of barnacles between E. imbricata and C. mydas. However, there was a significant increase in the number of barnacles with increasing size class in both E. imbricata and C. mydas. Epibiont biodiversity was significantly higher on E. imbricata but did not increase with size class for either species. Such findings indicate that the distinct life histories of C. mydas and E. imbricata may lead to varying degrees of epibiont accumulation.

This student research was retrieved from Physis: Journal of Marine Science V (Spring 2009)19: 32-36 from CIEE Bonaire.

Abstract:

Sponges are major epibionts of mangrove roots in the Caribbean. Mangrove sponge communities in the Caribbean mainly consist of species that are typical to this habitat and community compositions often differ from those found on coral reefs nearby. Heterogeneity in species distributions between locations and within locations between roots is often reported. This study quantifies the diversity and abundance of mangrove associated sponges in the inner bays of Curaçao and Aruba and correlates variability of regional sponge diversity with environmental variables measured along the surveyed sites. Tannin concentrations vary between mangrove roots, and were correlated to sponge cover as a possible cause for habitat heterogeneity on a smaller scale. A total of 22 species was observed. Heterogeneity in species richness and abundance was apparent, and several sponge species were restricted in their depth of occurrence. Statistical data reduction suggests that sponge diversity may be partly explained by the distance towards adjacent reefs and to the degree of eutrophication, in which the latter is comprised of rate of planktonic respiration, total carbon and turbidity. Tannin concentrations did not determine within locality species heterogeneity as a priori postulated, but were positively related to sponge cover for reasons not yet elucidated.